The present invention relates to the cleaning of process residues from chamber components that are used in substrate fabrication process chambers.
In the fabrication of electronic circuits, semiconductor, dielectric, and conductor materials, such as for example, polysilicon, silicon dioxide, aluminum or tungsten silicide, are formed on a substrate by, for example, chemical vapor deposition (CVD), physical vapor deposition (PVD), oxidation, and nitridation processes. In CVD processes, a reactive gas is used to deposit material on the substrate, and in PVD processes, a target is sputtered to deposit material on the substrate. In oxidation and nitridation processes, an oxide or nitride material, for example, silicon dioxide or silicon nitride, respectively, is formed on the substrate by exposing the substrate to a suitable gaseous environment. In subsequent processes, a patterned mask of etch-resistant material is formed on the substrate by lithographic methods, and the exposed portions of the substrate are etched by an energized gas to form patterns of gates, vias, contact holes or interconnect lines.
In these fabrication processes, process residues often deposit on the surfaces of the components in the chamber. The composition of the process residues may depend upon the composition of the process gas, the material being deposited or etched, and the composition of material on the substrate. Typically, the components are periodically removed from the chamber and cleaned with a solvent or an acidic or basic solution before being reassembled into the chamber. However, in certain fabrication processes, the process residues formed on the component have a composition that is difficult to clean, and consequently, they gradually accumulate on the component, eventually resulting in failure of the component. For example, when an electrostatic chuck forms the top portion of a substrate support and is exposed to the deposition of process residues, the residues deposit into the holes and other crevices of the electrostatic chuck to clog up the holes and result in failure of the chuck. Residues that have a chemically hard composition, such as sputtered material that deposits on the substrate support in certain PVD processes, are often difficult to clean off from the electrostatic chuck component that is in the line of sight of the sputtering target. Furthermore, when the cleaning solution comprises chemically aggressive solvents, the cleaning solution can damage the component during cleaning.
Thus, it is desirable to have a process to effectively clean process residues formed on a substrate processing chamber components, especially the chemically hard process residues. It is further desirable to prevent or reduce damage to the component during the cleaning process.
A method of cleaning process residues from the surface of a substrate processing chamber component holes therein. In the method, the component is at least partially immersed into a cleaning solution comprising hydrofluoric acid and nitric acid, and a non-reactive gas is passed through the holes to prevent the cleaning solution from back-flowing into the holes during the cleaning process.
A method of cleaning sputtering residues from the surface of an electrostatic chuck having gas ports therein comprises at least partially immersing the electrostatic chuck into a cleaning solution comprising hydrofluoric acid in a concentration of at least about 1 percent and nitric acid in a concentration of at least about 20 percent; and flowing nitrogen through the gas ports in the electrostatic chuck at a pressure of at least about 2 psi.